Public servants have complained of "a chilling effect" on democracy after Associate Health Minister Casey Costello accused health officials of undermining her efforts.
It comes after Health Minister Shane Reti on Tuesday morning joined Costello and Prime Minister Christopher Luxon in questioning the professionalism of ministry staff.
Ministry emails, revealed by 1News on Monday, showed a top advisor criticised the quality of information Costello provided to justify cutting tax on heated tobacco products.
The staffer wrote: "It's not so much that all of the studies are crap... [but that they are] selective... not up to date... and don't represent current evidence".
In response, Costello said the emails showed: "yet again, officials undermining the government's harm-reduction approach to reducing smoking rates."
"I have spoken to the Director-General about the importance of maintaining public sector standards of integrity and political neutrality," she said.
A ministry spokesperson told RNZ that director-general Diana Sarfati had subsequently apologised to Costello for "the unprofessional nature of the comments" and did not represent an official ministry position.
PSA and Labour hit back at minister's criticism
Public Service Association national secretary Kerry Davies said Costello's remarks were outrageous and "unacceptable within our democratic system".
"Officials are there to give robust advice so ministers can carefully weigh all the evidence and make good decisions," Davies said in a statement.
"In this case, the official with expertise in this matter was simply doing the job expected of her by taxpayers. She was pointing out the flaws in evidence the minister herself provided to justify a $200 million tax break for tobacco companies."
Davies said the PSA would formally complain to the incoming Public Service Commissioner, fearing the minister's attack would have "a chilling effect".
"Here we have an inexperienced minister intimidating officials because she is simply unhappy with their advice," she said. "How is that good for our democracy?"
Speaking to reporters at Parliament, Labour health spokesperson Ayesha Verrall said the official's actions did not warrant an apology.
She pointed out that the health advisor had backed up her analysis with extensive evidence: "When did it become wrong, in internal emails, to call something that is crap, crap?"
Verrall said Costello should not be surprised by the scrutiny of her actions given she was overturning "decades of public health consensus" on tobacco harm.
Costello: 'It wasn't all crap'
Addressing reporters at Parliament on Tuesday afternoon, Costello described some of the ministry's work on smoking reform as "unhelpful", including the latest correspondence.
"It was just revisiting stuff that didn't need to be revisited," she said.
"This process has been difficult. As you've seen, we've had leaked documents. We've had apologies given again and again."
Costello disputed the characterisation of the information she provided - "it wasn't all crap" - and said the PSA and Labour had misunderstood the matter.
"If there wasn't a problem, the director-general wouldn't have apologised. She's acknowledged that there was an issue."
Costello said she considered the apology to be "the end of the matter" and praised the "fantastic people" on the frontline working to help people quit smoking.
Health Minister, Prime Minister also unimpressed with ministry
Also speaking at Parliament, Reti said he understood Costello's frustrations. He said public servants needed to show appropriate "composure" and get behind collective decision-making.
"You just have to question whether that [language] was professional," Reti said.
"Free and frank advice is what you expect from your officials, I don't reconcile from that, but there are professional ways to convey that information."
Reti said the Director-General had reassured him she was ensuring appropriate policies and procedures were in place.
Separately, Luxon said Costello had legitimate questions about the ministry's conduct and pointed to their separate failure to inform Costello about a conflict of interest.
"They've been unacceptable, utterly unacceptable," Luxon said.
NZ First leader Winston Peters last month identified a different health official working on tobacco reform as being Verrall's sister-in-law and claimed Costello had never been informed of the conflict.
In response, the ministry defended its staffer, saying she had followed all the correct rules, but that the ministry had failed to pass it on.
In that case, Labour also savaged Peters for naming and attacking a public servant who could not defend herself and had done nothing wrong.
Responding to the allegations in person for the first time on Tuesday, Verrall categorically denied her sister-in-law had ever leaked her anything: "Absolutely not, she is totally a professional."